Measurement of flame temperature using active and passive tunable diode laser absorption spectroscopy (TDLAS)

Reconstruction accuracy is a crucial indicator for assessing the combustion conditions in combustion diagnostics. Existing flame-temperature measurement methods require comparison and verification using simulations, infrared thermal imaging cameras, and thermocouples, which increase measurement complexity and reduce efficiency. This study introduces a method based on tunable diode laser absorption spectroscopy (TDLAS) that utilizes an array sensor to capture specific absorption and radiation spectral signals to measure the combustion field temperature. Active and passive spectral information at different temperatures was obtained through calibration experiments. The temperature field of the K+-doped premixed stable flame was imaged. The difference between the active and passive spectral temperature field images did not exceed 8%, and the maximum relative error compared to the thermocouple measurements did not exceed 6%, demonstrating good reconstruction accuracy. Simultaneous active and passive spectral temperature measurements provide a novel approach for developing high-precision flame measurements and reducing system complexity.